Influence of the Process Parameters on the Properties of Cu-Cu Ultrasonic Welds

Ultrasonic welding (USW) is a solid-state welding process based on the application of high frequency vibration energy to the workpiece to produce the internal friction between the faying surface and the local heat generation required to promote the joining. The short welding time and the low heat input, the absence of fumes, sparks or flames, and the automation capacity make it particularly interesting for several fields, such as electrical/electronic, automotive, aerospace, appliance, and medical products industries. The main problems that those industries have to face are related to the poor weld quality due the improper selection of weld parameters. In the present work, 0.3 mm thick copper sheets were joined by USW varying the welding time, pressure, and vibration amplitude. The influence of the process variables on the characteristics of the joints and weld strength is investigated by using the analysis of variance. The results of the present work indicate that welding time is the main factor affecting the energy absorbed during the welding, followed by the pressure and amplitude. The shear strength, on the other hand, resulted mostly influenced by the amplitude, while the other parameters have a limited effect. Regardless the welding configuration adopted, most welds registered a failure load higher than the base material pointing out the feasibility of the USW process to join copper sheets.

Automated summary

Ultrasonic welding is a solid-state welding process that uses high frequency vibration energy to generate internal friction and local heat to join workpieces. It is particularly attractive for industries such as electrical/electronic, automotive, aerospace, appliance, and medical products due to its short welding time, low heat input, absence of fumes/sparks/flames, and automation capacity. The main challenge in these industries is the poor weld quality caused by improper selection of weld parameters. This study investigates the influence of welding time, pressure, and vibration amplitude on joint characteristics and weld strength when joining 0.3 mm thick copper sheets using ultrasonic welding. The results show that welding time is the most significant factor affecting energy absorption during welding, followed by pressure and amplitude. Shear strength is mainly influenced by amplitude, while the other parameters have limited effect. Regardless of the welding configuration, most welds exhibit a failure load higher than the base material, demonstrating the feasibility of ultrasonic welding for joining copper sheets.